W Boson

Syllabus: General Studies Paper 3

Researchers have announced that they have made a precise measurement of the mass of the so-called W boson.

What did the researchers find? Why is it significant?

They stated that the W boson is slightly heavier than that predicted by the so-called Standard Model of particle physics.

• This result is highly significant because this implies the incompleteness of the standard model description.

What is the standard model description?

The Standard Model of Particle Physics is scientists’ current best theory to describe the most basic building blocks of the universe. It explains how particles called quarks (which make up protons and neutrons) and leptons (which include electrons) make up all known matter.

• The Standard Model explains three of the four fundamental forces that govern the universe: electromagnetism, the strong force, and the weak force.

Why is the standard model believed to be incomplete?

• It gives a unified picture of only three of the four fundamental forces of nature. It totally omits gravity.
• The model does not include a description of dark matter particles. So far these have been detected only through their gravitational pull on surrounding matter.

What is W Boson?

Discovered in 1983, the W boson is a fundamental particle.

Together with the Z boson, it is responsible for the weak force.

The W boson, which is electrically charged, changes the very make-up of particles.

It switches protons into neutrons, and vice versa, through the weak force, triggering nuclear fusion and letting stars burn.

In contrast to the photon, which is massless, the W bosons are quite massive, so the weak force they mediate is very short ranged.